This is Steven Salzberg's blog on genomics, pseudoscience, medical breakthroughs, higher education, and other topics, including skepticism about unscientific medical practices. Here's where I can say what I really think about abuses and distortions of science, wherever I see them.

Do we all need PSA tests?

Say your doctor offers to run a PSA test, which might detect early signs of prostate cancer. The test is free to you, because insurance covers it. And you're already getting a blood test to measure cholesterol, so the cancer test doesn't involve any extra pain. Why not? And by the way, the American Urological Association recommends regular PSA screening for all men over 40. Based on this information (or less), millions of men get a PSA test every year.

But hold on. Suppose your doctor tells you a different story. First he explains that a recent, large-scale US study looked at the effect of annual PSA screening on more than 75,000 men, and found no benefit at all. A separate large study in Europe showed a very small benefit, but only in 2 of the 7 countries participating in the study. Suppose your doctor also explained that if you have a positive PSA test, there's an 80% chance that it will be false - that you won't have cancer.

Suppose your doctor also explained that "PSA-based screening leads to a substantial overdiagnosis of prostate tumors" and that treatment usually requires surgery. The effects of treatment are serious: 20-30% of men treated with surgery and radiation suffer from long-term incontinence and erectile dysfunction.

Prostate cancer tends to grow so slowly that many men with prostate cancer should not be treated at all. Unfortunately, once someone knows he has cancer, there's a very good chance he will elect treatment, even though we can't really tell if treatment will help.

"there is moderate certainty that the benefits of PSA-based screening for prostate cancer do not outweigh the harms." (USPSTF, Annals of Internal Medicine, 22 May 2012)

This recommendation, although based on a thorough assessment of risks and benefits, was met with howls of protest from urologists, who conduct most of the prostate cancer screening and treatment in the U.S. and elsewhere. The American Urological Association stated bluntly:

"The AUA is outraged and believes that the Task Force is doing men a great disservice by disparaging what is now the only widely available test for prostate cancer, a potentially devastating disease."

The AUA also issued press releases and launched a lobbying effort, asking their members to contact the media and Congress. They even provided a sample letter for urologists to send to their representatives in Congress.

Unfortunately for the AUA, their responses contain a very slanted presentation of the facts. The AUA president's response emphasizes the studies that found a benefit for PSA testing, but ignores those that found no benefit. In addition to this cherry-picking, they make the misleading claim that the recent U.S. PLCO study found "a significant reduction of prostate cancer death rates," which it did not. In fact, the PLCO study found a higher death rate from prostate cancer in men who received PSA testing.
And the AUA statements ignore the very serious risks of prostate surgery; essentially they are pretending the risk is zero.

Why did the urologists react so strongly? The answer appears to be simple: money. Urologists make a lot of money on prostate cancer treatments. The USPSTF estimated that in the first 20 years of PSA testing, 1 million additional men were treated as a result of screening. And if the surgery is unnecessary, you don't get a refund.

So who are you going to believe? The Preventive Task Force report presents a thorough review, laying all the details on the table. Their members don't make a profit from prostate surgeries. Their report simply more credible than the knee-jerk reaction from the urologists' association. I'll let the Task Force have the last word:

"The harms of PSA-based screening for prostate cancer include a high rate of false-positive results and accompanying negative psychological effects, high rate of complications associated with diagnostic biopsy, and—most important—a risk for overdiagnosis coupled with overtreatment. Depending on the method used, treatments for prostate cancer carry the risk for death, cardiovascular events, urinary incontinence, erectile dysfunction, and bowel dysfunction. Many of these harms are common and persistent."

At my last checkup, my doctor asked if I wanted a PSA test. I told him no thanks.